Control of aeroplanes and the like



May 27,1930.

M. L. BRAMSON CONTROL OF AEROPLANES AND THE LIKE Filed Au flo, 1925 2 Sheets-Sheet 1 Ma 27, 1930. M. BRAMSON CONTROL OF AEROPLANES AND THE LIKE Filed Aug. 10, 1925 2 Sheets-Sheet 2 chine reaches or approaches an angle of Patented May 27, 1930 UNITED STATES. PATENT OFFICE MOGENS LOUIS BRAMSON, OF HENDON, LONDON, ENGLAND CONTROL OF AEROPLANES .AND THE LIKE Application filed August 10, 1925, Serial No. 49,396, and in Great Britain March 30, 1925.

This invention has reference ,to the control of aeroplanes and-like aerial craft and has for its object to provide improved means for automatically warning the pilot when the ma- 1ncidence at which a further increase in said angle of incidence would result in a decrease of the lift co-efficient of the machine and as a consequence lead to stalling of the machine.

Various means have heretofore been suggested whereby a warning of some description is given to the pilot when this condition of the machine is attained or is approaching 5 such as the provision of a visual or audible signal when the machine reaches a predetermined air speed. Visual or audible signals cannot be regarded as satisfactory in all cir cumstances for the reason that they may escape the attention of the pilot at the critical moment and in either case they must be interpreted by the pilot and translated into action of some kind to correct the condition of the machine to which his attention has been directed. Further it is manifest that the minimum air speed of the machine required to produce a lift equal to the weight of the machine will vary with that weight and in fact with all variations of load on the machine whether static or dynamic. If therefore any instrument be set to give an indication when a machine of a given load reaches say fifty miles per hour as the minimum speed consistent with safety then if the load is changed fifty miles per hour will no longer be the correct speed at which the instrument ought to function. The problem to be solved therefore presents two aspects, firstly that the warning signal shall be of such a nature that the possibility of the pilot failin; immediately to understand it shall be eliminated, and secondly that the warning signal shall not be dependent upon air speed but shall be actuated when the angle of incir dence of the machine approaches the value 1 corresponding to maximum lift co-eiiicient open to objectionthere remains therefore the sense of touch which if properly appealed to will ensure unfailingly that the pilot shall receive the signal and if such signal can be conveyed to the pilot by a force applied to him through some part of the machine with which normally he is always in physical contact and if furthermore such .force can be applied so that independently of the volition of the pilot it will tend automatically to decrease the angle of incidence of the machine then the problem which I have propounded will be solved.

With the considerations in mind which I have outlined the primary object of the present invention therefore is to provide means for warning the pilot of an aeroplane or the like positively and automatically when the machine reaches a predetermined angle of incidence.

With this object in view and such others as may hereinafter appear or are incidental thereto my invention in its broadest conception consists in the provision of means whereby a positive warning force is applied automatically to the pilot through the sense of touch when the aeroplane reaches a predetermined angle of incidence.

More specifically considered my invention is embodied in a construction whereby a positive force is applied automatically to the control-lever of the aeroplane or the like whenthis latter reaches a predetermined angle of incidence in such a manner that the controls of the machine will tend to be moved in the proper direction to prevent such angle of incidence being exceeded but without interfering with the complete control of the machine by the pilot the arrangement being such that the force applied to the controllever is of suflicient strength to actuate it unaided by the pilot and yet weak enough to be easily resisted by him or in other words my device is so constructed as to produce a definite force acting on the control-lever in a directiontending to operate the controls of the machine so as to decrease its angle of incidence. vThe tendency of this force on the control-lever to influence the controls of the machine is of course incidental to the functioning of the device as a whole as the primary purpose of causing the control-lever to move in the proper direction is that thepilot whose hand is always in contact therewith will not be called upon to interpret the signal so conveyed to him but will instantl become aware of the action which ought to e taken. At the same time he will be able quite easily to resist the aforesaid force and prevent any movement taking place if he so desired.

In order that the invention may be readily understood by those skilled in the art to which it appertains I will now proceed to describe in detail the best means now known to me for carrying my invention into practlce to which end reference should be had to the accompanying drawings in which Figure 1 represents a side elevational View partly in section of the relay and controllever operating-mechanism hereinafter more particularly described.

Figure 2 illustrates a sectional view on the line 2-2 of Figure 1 looking in the direction of the arrows and Figure 3 shows a sectional view taken on the line 33 of Figure 1 looking in the direction of the arrows.

Figure 4 is a plan view of the control element for the relay and Figure 5 is a side clevational view of the control element shown in Figure 4.

eferring first to Figures 1 to 3 the control-lever of the aircraft which is mounted for universal movement in the cockpit in the and is connected to the piston rod 2 of a piston 3 adapted for reciprocation in a cylinder 4 appropriately mounted upon the aircraft. One side of the piston 3 is continuously open to atmosphere by means of a port or ports 5 whilst the; opposite side is adapted to be placed in communication either with the atmosphere or with a source of air under pressure in the manner hereinafter described.

The cylinder 4 is craft as to be capable of free movement about the universal joint 6 carried by the lugs 7 and the latter being positively attached to a spllt sleeve 9 adapted to be secured to a cross brace or similar part of the air craft. The free end of the piston rod is also adapted to have free movement through the universal joint 10 which is connected through the lug 11 tti a sleeve 12 mounted upon the control-lever Conveniently mounted upon the cylinder 4 is a relay indicated as a whole by the ref erence numeral 13 which in the particular usual manner is designated by the numeral 1' construction shown comprises a cylinder in the interior of which is a diaphragm 14; operatively connected with a double piston valve 15. The relay 13 is adapted to be'in continuous communication through a nipple 1'; with a source of air under pressure as for instance an air-reservoir fed by a mechanically driven so mounted upon the airb or air-driven pumpand the valve 15 is adapted in one of its positions to, permit air under v pressure to act on the underside of the piston 3 to impart an impulse to the control-lever and warn the pilot through his sense of touch or topermit atmospheric pressure to act on the underside of the piston 3 through ports 16 so that the piston may move freely in its cylinder and not impede movement of the control-lever.

With the double piston-valve in the position shown in Figure 3 air under pressure admitted through the nipple 17 is prevented from entering the cylinder 4 and passes through a bye pass 18adapted to be adjusted by screw 19to the space beneath the diaphragm 14 which communicates by way of a nipple 20 and appropriate pipe connections- -not shown-with a suitable devicesuch for instance as a device responsive to changes in the angle of incidence of the airstream--for controlling therelay.

Any convenient form of device may be utilize-d for this purpose and in Figures 4 and 5 I have illustrated what I now consider to be a preferred form thereof. This device comprises essentially a vane 21 so mounted as to be influenced by the air-stream to cause the relay 13 to operate suddenly to admit air from the -air reservoir behind the piston 3. In the present instance this is accomplished by mounting the vane at the end of a lever 22 pivotally mounted about an axis or pivot 23 depending from a hollow tubular member 24 adapted for pivotal movement about an axis 25 parallel with the axis 23 in a frame member 26 adapted to be secured by brackets 27 to one of the wing struts or other convenient part of the aircraft.

The frame member 26 is provided with an arcuate slot or slots 28 so as to enable the tu-' bular member 24 and consequently the vane 21 to be initially adjusted as desired. A fine adjustment for the vane is also provided y a screw 29 ina member 30 depending from the tubular member 24.

The hollow tubular member 24 is adapted to be connected by a flexible tube or the like with the nipple 20 and is thus placed in communication with the underside of the. diaphragm 14 and is provided in a convenient position with a spring controlled mushroom or poppet valve 31 adapted to be opened by the lever 22 in its upward movement due to the movement of the vane under the influence .of theair-stream when the predetermined angle of incidence is reached. The element 24 and consequently the vane 21 being of course so adjusted that the vane 21 will operate at the predetermined angle of incidence of the air-stream and until that angle has been reached the the lever 22 remains in its lowermost position. lmn'iediately however the predetermined angle is reached the lever 22 moves positively upwards and contacting IOU with the valve 31 opens the ports 32 to atmosphere.

In the operation of my improved device and assuming the parts to be in normal position and the aircraft to be travelling upon an even keel the valve tion shown in Figure 3 and air under pressure from the air reservoir will fill the space at the underside of the diaphragm 14 the passage 20 and the hollow tubular element 2-1 of the control device the valve 31 being closed under influence of its spring and the lever 22 being maintained in its lowered position by the airstream. If now the angle of incidence of the air-stream increases sufiiciently to cause an upward force to be exerted on the vane the lever will be moved sharply upwards and so open the valve 31. The pres sure beneath the diaphragm will immediately fall to atmospheric with the result that the diaphragm will move to actuate valve 15 to permit air under pressure to be admitted to the cylinder at to actuate the piston 3 and apply an impulse to the control-lever l to warn the pilot by his sense of touch.

That force will continue to be exerted on the control-lever so long as the valve 31 remains open that is so long as the force exerted upon the vane by the air stream maintains the vane in the uppermost position. \Vhen however the incidence of the machine is decreased by an amount equal to the angular movement allowed to the vane between the adjustable stop 29 and the port 32 the force exerted by the air stream -upon the vane willonce more deflect the vane downwards to its original position against the bottom stop. Simultaneously the valve 31 will close and the relay 13 operate to release to atmosphere the pressure previously admitted to the rear of the piston 3. The pilot therefore will feel the sudden relief of the force previously applied to the control-lever and recognize it as an indication that the machine is now at a safe margin from the stalling point.

It will be observed that the vane being situated tip-stream with reference to its polnt of pivotal suspension it is therefore unstable with reference to the air stream. The action of the controlling device is therefore definite or in other words equilibriunr can exist only in the two extreme positions of the vane and any movement once commenced from one extreme position must needscontinue until the other extreme position is reached.

Means may be provided whereby the device may be cut out of action wheirdesired as when taking off or landing for instance. One way of effecting this is by the provision of a valve conveniently located in the tube 33 connecting the passage 20 of the relay with the tubular element 24 by way of the nipple 34.

It is to be understood that although in 15 will be in the posi-' ing said vane and the foregoing description a vane influenced 'by the angle of incidence of the air stream aerial craft means including a device settable" to operate at one predetermined angle of incidence of said craft for applying a sudden warning force automatically to the pilot through the sense of touch when said craft reaches said predetermined angle of incidence.

2. In or for use'with an aeroplane or like aerial craft having a control-lever for controlling the movements of the craft in the air, means including a device settable to operate at one predetermined angle of incidence of said craft for applying a sudden warning force automatically to the control lever when said predetermined angle of incidence is reached.

In or for use with an aeroplane or like aerial craft means settable to operate at one predetermined angle of incidence of said craft and means controlled by said first mentioned means for applying a sudden warning force to the pilot through the sense of touch when said craft reaches said predetermined angle of incidence.

4. In or for use with an aeroplane or like aerial craft means including avane mounted so as to be susceptible to the air-stream and settable to operate at one predetermined angle of incidence of the craft and relay means controlled by said first mentioned means for causing a warning force to be applied suddenly to the pilot through the sense of touch when said craft reaches said predetermined incidence angle. I

5. In or for use with an aeroplane or like aerial craft having a control lever for alfecting longitudinal and lateral control surfaces on said craft, a vane pivotally and unstably mounted with reference to the air-stream and means including a relay operatively connectsaid control lever, said vane being so set with reference to the craft and being so associated with the relay that a sudden warning force is applied to. the control lever when the craft reaches an angle of incidence such that a further increase'in said angle would result in a decrease of the lift coefficient of the craft. v

6. In an aeroplane the combination with the usual control lever for affecting longiand outlet passages,

tudinal and lateral control surfaces on said craft of means settable to operate at a predetermined incidence angle of said craft and means for applying a sudden warningforce to the control lever, said last mentioned means being caused to operate by said first mentioned means when said craft reaches said predetermined angle of incidence to apply said force to the control lever in a direction tending to operate the controls of the machine to decrease said angle of incidence unless deliberately opposed'by the pilot.

7. A relay device comprising fluid inlet a double seated valve controlling the flow of fluid through said relay, a pressure responsive element connected to said valve, a bye-pass from said inlet to the side of said element remote from said valve and atmospheric passages associated with part of said valve, the arrangement being such that a pressure may be built up on the side of the pressure responsive element remote from the valve to interrupt the flow of fluid through the relay and place the outlet passage in communication with the atmosphere. i

8. A relay device comprising inlet and outlet pressure fluid passages, passages communicating with the atmosphere, at double seated valve, a diaphragm connected with said valve. a bye-pass from the pressure fluid inlet passage to the side of the diaphragm remote from said valve whereby pressure may be built up on the side of the diaphragm remote from the valve to interrupt the flow of pressure fluid and place the pressure fluid outlet passage in communication with the atmosphere.

9. In combination with an aeroplane or like aerial craft having a control lever, means including a vane pivotally and unstably mounted on said craft with reference to the air stream and means including a relay actuatable by said vane for causing a warning force to be applied suddenly to the control lever. said first mentioned means being setta- 'ble to operate said second mentioned means when said craft of incidence.

.10. lncombination with an aeroplane or like aerial craft having a control lever, a vane pivotally and unstably mounted with reference to the air-stream, a cylinder having a piston operatively connected with the control lever and a relay device interposed between said vane and cylinder, said vane being settable to operate at a predetermined angle of incidence of the craft and said relay being operatively associated with said vane whereby a positive force may be applied to the control lever when the machine reaches said predetermined angle of incidence.

11. For use with an aeroplane or like aerial craft a control device comprising a vane mounted for pivotal movement about a point reaches an unduly large angle locateddoWn-stream with reference to the vane when the device is .positionedupon the craft, a cylinderhaving a piston located therein, and a relay for of pressure fluid to said cylinder, said vane being settable to operate at an angle of incidence of said craft such that a further increase in said angle would result in a decrease in the lift co-efiicient of said craft to actuate said relay to admit pressure fluid to said cylinder for the purpose specified.

12. For use with an aeroplane or the like having a control lever, a device comprising a vane mounted for pivotal movement about a point located downstream, with reference to the vane when the device is positioned upon the craft, a cylinder having a piston for operative connection with said control lever and a relay for controlling the supply of pressure fluid to said cylinder, said vane beingsettable to operate at an angle of incidence of said craft'such that a further increase in said angle would result in a decrease in the lift coeflicient of said craft to actuate said relay to admit pressure fluid to said cylinder whereby a force is exerted upon said control lever which unless deliberately opposed by the pilot tends to decrease said angle of incidence of said craft.

13. A control device for aircraft comprising a pivotally mounted vane, which when mounted upon said aircraft is unstable with reference to the air stream and capable of occupying only one or other of two extreme positions under the influence of said air stream and relay actuating means for association with the vane in one position.

14. A control device for aircraft comprising a vane pivotally mounted upon a member adjustably mounted on a bracket for attachment to the aircraft and co-operating relay actuating means on said vane and member said vane being situated upstream with reference to its point of pivotal suspension when said device is positioned upon said aircraft so as to be capable of occupying only one or other of two extreme positions under the influence of said air-stream.

15. A control device for aircraft comprising'a bracket for attachment to the aircraft, a member adjustably mounted on said bracket, a lever pivotally mounted adjacent one end upon said member, a vane mounted upon said lever at its other end and co-operating relay actuating means on said lever and member, said vane being situated upstream with reference to its pivotal suspension when said device is positioned upon saidaircraft so as to be capa-ble'ofoccupying only one or other of two extreme positions under the influence of said air-stream.

16. A control device for aircraft comprising a tubelike member pivotally mounted on a bracket for attachment to an aircraft and controlling a supply I said valve pivotally mounted upon said member, said vane being situated upstream with reference to the point of pivotal suspension when said device is positioned upon said aircraft.

17. In an aeroplane or like aerial craft the combination with the usual control lever for controlling the movement of the craft in the air of a vane mounted on said craft so as to be susceptible to the influence of the upstream and so that it is sensitive to a predetermined angle of incidence ofsaid craft, a cylinder having a piston operatively connected with said controllever and a relay device for controlling the flow of pressure fluid to said cylinder interposed between said vane and said cylinder said vane operating to cause said relay to admit pressure fluid to said cylinder and apply a sudden warning force to said control lever when said craft reaches said predetermined angle in incidence.

18. A control device for aircraft comprising a pivotally mounted vane adapted to be mounted on the craft so as to be susceptible to the airstream created thereby during flight, said vane being situated upstream with reference to its point of pivotal suspension so as to be capable of occupying one or other of two extreme positions under the influence of said air stream.

19. In combination with an aeroplane or like aerial craft means settable to operate at one predetermined angle of incidence of said craft, means for applying a positive warning force to the pilot through his sense of touch when the craft reaches said angle of incidence, and means actuated by said first mentioned means at said predetermined angle .of incidence for causing operation of said second-mentioned means.

MOGENS LOUIS BRAMSON. 

